In a wireless communication system, a base station refers to a device for providing services for a terminal, and may communicate with the terminal via an uplink and/or a downlink, wherein the downlink (forward) refers to a direction from the base station to the terminal, and the uplink (backward) refers to a direction from the terminal to the base station. In usual applications, a plurality of terminals may simultaneously send data to the base station via the uplink, and may also simultaneously receive data from the base station via the downlink.
In mobile networks, wireless coverage quality is an important guarantee for the terminal to enjoy high-speed data, audio services and video services. At present, in order to realize the seamless coverage of wireless networks, the problems of indoor coverage and hotspot coverage need to be emphatically solved. The following two solutions can be mainly used for the coverage, one of which is increasing the number and density of Macro BS (viz. increasing the number and density of Macro Cell); the other of which is installing an indoor small base stations with low emitting power such as Femto BS (also referred to as personal BS) (also referred to as Femto Cell), a Pico BS (also referred to as Pico Cell), a Micro BS (also referred to as Micro Cell), or the like.
According to the Shannon principle, in the case where conventional Macro BSs are used for coverage, the occupation amount of frequency spectrum will approximate the capacity limit for the use of the frequency spectrum; even if the number of the Macro BSs with larger power is further increased, few improvements will be made for the indoor coverage and more irradiation pollution will be caused instead. While using small base stations such as Femto BSs, Pico BSs, Micro BSs, or the like may not only solve the problems of indoor coverage and hotspot coverage very well but also improve the system capacity based on the current frequency spectrum resources.
In Long Term Evolution (LTE) and IEEE 802.16 series standards, the Femto BS can either provide services for all the terminals (this type of Femto BS is called an Open Subscriber Group (OSG) type Femto BS) or provide services only for a group of specific authorized terminals (this type of Femto BS is called a Closed Subscriber Group (CSG) type Femto BS). The CSG type Femto BS can be divided into two types, CSG-Closed and CSG-Open, wherein the CSG-Closed type Femto BS generally provides services only for specific authorized terminals or terminals needing urgent services, while the CSG-open type Femto BS can provide services for other unauthorized users on the premise of ensuring the quality of service (QoS) for specific authorized users.
For facilitating a terminal to select a suitable Femto BS as a serving base station, an information list (also referred to as White List) including Femto BSs accessible to the terminal may generally be maintained in the terminal. The information list generally contains identifier information of each related Femto BS, and the identifier information may be either a BS JD of the Femto BS or a Closed Subscriber Group Identifier (CSG_ID) of the Femto BS. When the Femto BS is used by home users, the terminal generally maintains the BS_ID of the Femto BS; when the Femto BS is employed in an office building of an enterprise or some entertainment venues, hundreds of the Femto BSs might be present, which makes it difficult for the terminal to update in real time a list based on BS_ID information according to locations, and a large amount of terminal storing resources need to be occupied. Therefore, in this case, multiple Femto BSs can share one CSG ID, and the terminal can judge whether the Femto BS to be selected is a Femto BS accessible to the terminal according to the CSG ID information stored in the information list.
However, not all the Femto BSs have CSG IDs. Thus, it is necessary to allow the terminal to be informed of whether the Femto BS to be selected has a CSG ID and the BS type thereof, so as to facilitate the terminal to subsequently judge whether the Femto BS to be selected can provide services for the terminal according to the BS identifier or CSG ID. However, in the present applications, the terminal is not able to know the more specific BS type and whether the Femto BS has a CSG ID, and thus cannot judge according to the BS identifier or CSG ID in a subsequent process whether the Femto BS to be selected can provide services for the terminal.